linux-kernel - do_filp_open fails to detect dentry revalidate of 1 and crashes

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Date:	Thu, 2 Oct 2008 00:17:16 -0600 (MDT)
From:	jmerkey@...fmountaingroup.com
To:	linux-kernel@...r.kernel.org
Subject: do_filp_open fails to detect dentry revalidate of 1 and crashes

On assignment of a negative dentry, do_filp_open will crash with an oops
in do_sys_open because do_filp_open returns "1" from revalidate rather
than properly detect a negative dentry which has a dentry revalidate
function before the file actually exists.

Easy to reproduce.  Create negative dentry and attach a revalidate
function which returns 1 instead of 0 on non-existent file entry.   The
convoluted code in do_filp_open does not detect dentry errors in all cases
properly.

Jeff

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